1. Field of Invention
The present invention relates to a remote power control circuit, more particularly to a remote power control circuit for the DDC device (such as for display driver control) of a computer.
2. Description of Related Arts
Regarding the power regulation or controlling, it is very important for the computer and its related applied device, such as the display and the corresponding power switching system. As described a prior art in the U.S. Pat. No. 5,675,364, the computer system with communication path from the display to the host system is disclosed. It applied a basically method to implement the computer related device by power switching or saving. It majors to a host computer to apply a screen display's power using steps. The main feature as the wake up circuit is indicated inside for the computer cooperated with the display. The on-off switch with the video signal are also disclosed inside its related Figure and the specification. Also the on-off cycle is a suitable series of steps for the power control of the display. But the above system did not directly regard to the DDC display and not suitable as remote power on/off control.
As described a prior art in the U.S. Pat. No. 5,764,547, it is a power control method with the structure about a monitor and a switch combined a host computer, which the computer has a detection circuit and a soft-start power by using a method with display data having a connection to the switch to send a display activating signal and further to activate the host computer by a display data signal. Wherein the three way power switch system is included the applied method to turn on/off the an entire computer system and with one single switch. And the soft-start circuit detects the signal from a DDC (display data channel) capable monitor, and the motor having the near switch for power control. Also the power control is capable from the host computer. But the above system is not suitable for a coding signal to power on/off control to the DDC display.
As described a prior art in the U.S. Pat. No. 6,125,449, a power state control architecture is described for computer control to the motor connection with power control button with a video cable. The power state includes the on/off and intermediate state (power sleep). The system comprises a monitor, a power control switch, a power management device, wherein the power management device comprising: a detector coupling to the monitor, a controller configured to change the power state of the computer, a video cable connected to the monitor and the power control button connected on the video cable. Also the above system is not suitable for a coding signal to power on/off control to the DDC display.
Referring to FIG. 1, it illustrates the conventional computer system, including a power supply 110, a motherboard 120, and a display 130. The connection between the motherboard 120 and the display 130 is a display data channel (DDC) for communicating the graphics data between them. The motherboard 120 includes a power supply control logic 121 to control the on/off or reset of the power supply 110. The power supply control logic 121 is controlled by the power supply switch 122 or reset button 123. If a user sitting in front of the display wants to shut down or reset the computer, he/she has to presses the switch 122 or reset button 123.
Referring to FIG. 2, it is similar to FIG. 1, but there is a graphics processing unit (GPU) 140 between the motherboard 120 and the display 130. The DDC is also used for the communication for them.
No matter in which circumstances, to shut down or reset the power supply of a computer, the user has to approach to the power supply switch 122 or reset button 123, both are attached to the mainframe of a computer system by in person. If the display is not in the same room with the mainframe, or they are apart for about tens meters or even farther, it is very inconvenient for the user to shut down or reset the power supply. Therefore, there is a need to provide a new system to resolve the problem.